Think about it! History was changed three times, once by Biff, a second time by Marty traveling back to 1955 to stop Biff, and again in 1885 by Marty and Doc in Back to the Future 3. The new 2015 that resulted is basically our timeline as it exists now. In 2015, a Back to the Future 4 will be released in which Marty Jr accidentally goes back to 1985.

The 2015 of Back to the Future Part II was erased by paradox.

A lot of them! Jennifer saw herself, Biff returned to a 2015 that by the new timeline he created in 1955, was impossible and thus Biff got erased. Marty and Doc then traveled back in time using a time machine that should no longer exist in the timeline they exist in now, however, Old Biff's desire to return to 2015, results in a possible timeline where he does, simply by punching "in "last time departed". In this possible timeline, Marty and Doc, enter the time machine with the desire that they go to there 1985. However, Doc Fails to notice that the time machine's "last date traveled" is set to 1955. The time machine's computer then calculates 1985 from the 1955 it created. This erased both Marty and Doc's 1985, but not, from the time machine's perspective, Marty and Doc. This also erases the 2015 they just left. By traveling back to 1955 from the Alternate 1985, They rewrite history agian, creating yet another alternate 1985, and another alternate 2015. The timeline was able to create a stable time loop where because Doc died soon after coming to town, history was not sufficently altered to erase Marty. Because of Doc's Earlier Paradox encountering his older self, forming a Quantum Entanglement if you will, was drawn back to Marty in a self correcting loop. Since Marty failed to die, this self correcting time loop, was erased, creating an alternate 1955, 1985, and 2015, The Alternate 1985 of Eastwood Ravine was one of self correcting Paradoxs. Since Marty was sucessful, the stable timeloop of 1955 was allowed to continue along a similar enough path that they still buried the time machine in 1885 for Marty to dig up in 1955, allowing marty to go back to 1885. But agian, 1985, is the 1985 that the time machine would calculate which is the most correct, however, the only evidence for the 2015 it's previously been to was destroyed, and thus it can't calculate it's causality, all this leaves that 2015 open, as long as Marty doesn't use his knowledge of the Future to change history. But Marty did, and didn't race Needles, and thus the 2015 of "Your Fired" is erased, but the paper isn't because the paper of 2015 was recycled from paper of 1985. A new 2015 is created because Marty and Jennifer reject the 2015 they left. Since the 2015 they left was still unstable from the tripple paradox of Jennifer seeing from herself, Old Biff using the "Last Date Departed" and Marty and Doc using the Time Machine to Return to 1985, was hit by waves of instability coming from a massivly unstable 130 year long timeline with multiple self correcting time loops. The Final Paradox, the straw that broke the Universe's back was Marty and Jennifer using their knowledge to prevent it from happening. Meanwhile at an earlier point in the same timeline, Doc over many years, buys a steam engine, uses his knowledge of nuclear physics to very carefully create plutonium in the 19th century, hops in to the time machine with his wife and kids. Since this took place before Marty and Jennifer decide to use future knowledge to prevent futute events, thus spliting the Eastwood Ravine timeline, the steam engine would go to one of two 1985s, one where Marty and Jennifer get into the accident, and one where they don't. Since this is the one where they don't, that 2015 is rejected, and thus erased, and this current 2010s is the one we'll get, not the exponentally more immpossible 2015. The only X factor is where will Doc go in his Time Train. Do we exist in the "Eastwood Ravine" timeline? Is that timeline erased by Doc's next destination? And if so are we the timeline of that 2015, or one of the many 2015s that where erased?

The highest statistical likelihood, stemming from the majority of time travel experiences described in the English language, is that we are now in the timeline created by the Doctor when he showed up, behind the scenes, to save both the universe and the Milky Way galaxy (or Mutter's Spiral, if one prefers) from being destroyed by the number temporal causality paradoxes that you describe. As such, if the ravine is found, there is a strong possibility that it now reads "Smith Ravine".

Strickland thought George was a slacker because of his schoolwork arrangements with Biff.

Biff forces George to do his homework. Probably this means George has to do different assignments for himself, so that no one would think he was copying off Biff. These assignments would inevitably sometimes be not as good or even unfinished, hence the accusations of being a slacker.

In one timeline, Marty pulls off a successful Oedipus and becomes his own father.

This is the reason Marty's siblings where erased before he was. In one timeline, Marty, confused as hell, actually gave in and, you know, with his mother. He then decides to stay in 1955. He will then try to father alternate versions of his brother and sister, But because they would have inherited different genes from George then Marty did, they where impossible, thus they where gone the night of the dance. However, Marty was still possible. Unlikely but possible. Only possible through a sperm containing the exact half of the genes he inherited from his father joining with the exact same egg that made him. When he rejected this possible future in the car with his mother he began to erase himself again, because in that timeline his mother would go home from the dance disappointed. Only by either getting his mother and himself back together, or by getting his mother and his father together, could a timeline where Marty was possible come back into being.

Almost none of the films events actually take place.

Marty's brain is severely traumatized by the super-amp that blew him across the garage, sending him into a permanent fugue where he experiences all of the time travel adventures, despite actually being kept artificially alive in a hospital.

In 1955, Biff doesn't live with his grandmother.

He lives with his step-mother, Edna. He just calls her "grandma" as an insult.

This is in violation of the first rule of BTTF time travel: you can never see the effects of your own time travels before actually performing those time travels.

The whole premise of Back To The Future Part II is a violation of this rule, because Marty and Jennifer see their children despite, from an external perspective, having just disappeared for 30 years. They should not be able to see their children because they haven't travelled back in time to 1985 yet, nor got old enough to finish school, get married and have those kids in the first place.

No No NO! That only applies if they had opted to stay in the future.

This is because the ripple effect takes subjective time on the time traveler's part to take effect. One can travel into the future and meet his future self, but if he stays long enough, his future self will fade away... that is, until the time traveler returns to the past.

In what way does time travel have anything to do with whether or not Biff lives with his grandmother?

It has to do with the model of time travel featured in BTTF, which states that someone can never see the effects of his or her time travels until he or she actually performs those time travels. Marty's time travels in the game, which resulted in Edna Strickland's marrying Kid Tannen, had not yet occurred.

If one actually paid attention to the sign on Biff's grandmother's house, one would see that her name is Gertrude Tannen.

Doc risked his past by going back to warn Marty and Jennifer to fix their future.

First, it is canon that, after surviving the bullets in the new version of 1985 at the end of Part 1, Doc decides to go forward in history. It is presumed that he does disappear from the timeline during his trip.

It may be presumed that everything else happens "normally" until he returns — the future that we see in Back to the Future II really happened the first time around. For example, the car accident that we see not happen at the end of Part 3 does.

Perhaps middle-aged-Marty's psychological problems are partly related to the trauma of Doc having disappeared.

Doc reads the newspaper article about Marty Jr in jail and decides he must prevent it. He goes back to 1985 and picks up Jennifer and Marty, then goes forward. This would have caused timeline alteration, including a no-Jennifer-and-Marty universe; but the ripple effect "hasn't happened yet", in accordance with BTTF metaphysics. They necessarily visit the exact same 2015 as the one from which Doc departed. It is only afterwards that things diverge, with the usual weird risks of paradoxes and whatnot, which is why the future of III is unknown in film canon.

The risk is more visible with old-Biff's adventures. He goes back in time and gives the almanac to himself. When he goes forwards, one would think he would arrive in a rich-Biff timeline. He doesn't because, since he left 1955 before the branching point when Marty either does or doesn't successfully take the almanac back, the changes haven't rippled forward as fast as Biff rippled out of the timeline... It may be presumed that he has the heart attack because the rich-Biff died in middle age.

Old Biff died and faded away because - in the timeline he created - Biff was killed in 1996, per a DVD special feature. Quite probably by Lorraine (or at her request).

The Delorean door opening in Part II killed Biff.

In a deleted scene, we see old Biff dissappear after changing the timeline. that's because in A!1985, The door opening killed A!Biff, so Old biff didn't exist.

Doc is a Chessmaster who planned out the entirety of Part II and III to ensure a better future for Marty

At the very end of the third movie, when Doc comes back in the train with his kids, Jennifer asks him about the fax, and the fact that it erased. He says of course it did, the future isn't written yet you can make it whatever you please. In my mind, this kinda cheapened the entire second movie. Why bother going to the future to change what happened to Marty Jr if the future isn't set in stone and can be changed?

But...it wasn't pointless. Doc PLANNED the entire thing. Doc knew that Marty being a hothead about being called "chicken" resulted in a future that was...not really great. He wants Marty to get over this, but can't just say "You're going to be in a car race that Needles eggs you in to, you're going to hit a Rolls Royce and ruin your future." Doing that would cause problems, because as he says multiple times, no one should know too much about their own future. So instead, he comes up with a plan: set into action a chain of events that will cause Marty to mature, and get over his whole problem with being called chicken. So he uses his knowledge of how timelines and time travel works, and figures out this plan, that involves the entirety of Btt F 2 AND 3, that eventually gets Marty to mature. His tombstone just HAPPENS to be next to where the De Lorean is buried in 1955? No...he planned it that way. He let it be known that is where he wanted to be buried, so that Marty would see the tombstone in 1955 and plan to come back to the past, and that the events of part 3 would happen and allow Marty to get over his issues and not get in that accident. Another part of the theory is the malfunctioning Time Circuits in part 2. They worked just fine, he simply made it look like they weren't so he'd have an excuse to be sent back to 1885. When he was trying to land the De Lorean in 1955 after Marty burned the book, he says that he has to fly back around due to the wind, but in what we've seen of the De Lorean flying previously, it seems like it is able to do a vertical landing, akin to a harrier jet. So why suddenly does the wind matter? It doesn't. Doc knows that if he stays in the air he will get hit by lightning, and has the time circuits ready to go to 1885, as it is all part of his perfectly thought-out plan.

Doc is a total bad-ass, and one of the greatest Chessmasters ever committed to film, using his own death as part of his plan.

"Why bother going to the future to change what happened to Marty Jr if the future isn't set in stone and can be changed?"

In a way, this question answers itself. Because the future can change… one may as well "bother" to change the future. It just happens that Doc is cautious enough to not want to change the future "too much", so he doesn't try to prevent the Marty-Jr-in-jail timeline by simply warning young Marty about his future son and waiting thirty years.

Apart from that, this is very clever, though of course like nearly any plan in both film and real life, there seem to be many many ways it could have gone wrong.

It probably "went wrong" several times. Doc knows how to redo things/warn himself without paradox.

Doc's inventions created the futuristic 2015 of the movie.

The reason why the 2015 in the movie looks nothing like what the true year of 2015 will be is because we're in a reality with no Doc Brown. The man is a genius who is WAY ahead of his time and it's fairly likely that he'd be capable of many other inventions after mastering time travel. It's possible then that everything from hoverboards to hovercars and anything else you saw in that futuristic 2015 were all based on Doc Brown's prototypes. Still odd how cell phones or laptops don't exist in that reality though.

Cell phones and laptops may very well be children's toys in that reality.

In an alternate flow of technological development ushered in by Doc Brown the resources that would have gone into the things in the Prime timeline (ours, without Doc) that we take for granted were never invented. The financial resources that would have gone into developing cell phones instead went into developing hoverboards, etc. So while that universe seems to have technological advancements that would take our breath away, we also have technological advancements they would find amazing. There's always a karmic balance to messing with timelines.

More radically : the laws of physics work differently in the BTTF universe. Remember they have Time Travel in 1985. Doc may be a genius, but that means Time Travel was easier to understand in their universe than in our own, where there isn't even any theory of how it should work, if it is possible at all.

The DeLorean'sLED readout indicating the year is broken.

Specifically, the space which records the last digit of the year, which is why they can only travel to years ending in "5". (The time when Doc demonstrated the display with the years "1776" and "0000" was before it broke.)

Considering that there is no Year 0...yeah, it was probably broken then, too. It may have gotten broken when Doc entered "Dec 25 0000."

Of course there is a year zero, just not everyone calls it that. The number assigned to a year is an arbitrary convenience. It doesn't matter what label your calendar slaps on it, if the time machine knows to go back a certain number of years that's all that matters. Doc programmed his Delorean with a different calendar than the common modified Gregorian— there are several calendars that use a zero year to mark the birth of Christ.

Leaving out the instances of people traveling back to where they belong (the various trips back to 1985) and the instances of people trying to fix something (all of the other trips the movies followed), the only time travel in the movies that was intentional were Doc's first trip to 2015 and Old!Biff's trip to 1955. Doc probably just figured on thirty years being a nice round number for his trip forward, and Old!Biff probably just went back to 1985 because that was the year he turned 18 (and - due to the events of the first movie - the date had a certain significance for him). There's no reason to think that the machine can't travel to other years.

The DeLorean LED readout is merely a relative measurement.

Going to 0000 from anywhen AD would result in landing in -1 AD/1 BC

Or the Doc knows that conventionally, 1 BC is followed by 1 AD, but doesn't care.

As a somewhat maverick scientist it would make far more sense to him for there to be a year zero and anything before then to be negative years, so instead of following convention he just makes his own.

It might on the other hand simply have made things easier when designing the time circuits (or programming their firmware) to have a year zero than to make the readout go from -1 to 1 (effectvely) or even bother with "negative years"; some offhand comment the Doc makes (I think) in the third film about going back too far and being burned as a witch, suggests he's not interested in travelling back too far for comfort and it makes no sense to design the machine to go back millennia.

Doc Brown is The Doctor.

An eccentric old man, more then happy to take an impulsive teenager back and forwards in time with him, but still takes preventing paradox's very seriously. Pacifistic enough that knowing a group of Libyan terrorists is coming after him he uses the information to get a Kevlar vest, which would do nothing if the terrorists decided to shoot him in the head point blank, even though he could have easily set up a trap to kill them. He must have aged at least 35-40 years (based on estimated age of the kids on the train) between 1955 and the end of film yet he looks no older.there are about 200 years between episode 11 and 12 of doctor who season 6 during this time we know nothing about his whereabouts. alternatively it is made very clear that the doctors intention at the end of season 6 is to lay low for a while. oh and his nickname is doc. just saying.

Either that, or Doc Brown is the Doctor after his twelve regen limit is used up, and he's just living through the rest of the years. However, it is also possible that Doc Brown is just a human who was visited by the Doctor. Doc had a vision, and the Doctor just happened to take a liking to him—he "gently nudged" Doc in the right direction. On top of all that, the De Loreanhas to use the Time/Space Vortex in some way: one miscalculation, and your bright, shiny Time Machine goes flying off the face of the earth.

I would like to point out that the First Doctor and the Sixth Doctor have each shown a dislike for people calling them "Doc."

Also, the second guess has been jossed by the new series of Doctor Who, wherein the Doctor receives a new set of regenerations.

The Flux Capacitor doesn't make Time Travel itself possible, it makes it possible for a person.

The real function of the Flux Capacitor is to ensure that anyone traveling through time remains isolated from changes made to the time stream that may affect them. This is why Marty retains his memories from the "original" timeline and his Ripple Effect proof memory. Doc doesn't actually use the machine himself until the very end of the film and so his past was changed thanks to Future!Marty's involvement while Marty remembers things the way the used to be. This is also why Marty fades from time so slowly. In reality he should be the first kid in his family to fade because if they never married and had Dave they sure as hell aren't going to have Marty, but Marty was shielded from time's effects due to the Flux Capacitor.

The name of the device supports this - flux is a rate of movement or current (in effect - change) and a capacitor temporarily stores energy. So the Flux Capacitor makes perfect sense for the name of a device that stores temporal changes instead of letting them flow freely.

In a bizarre coincidence, the VW bus the Libyans drive is the exact same model and color as the kind DHARMA uses all over the island. Because rogue time travelers would cause DHARMA quite a few problems, they sent the Libyans to assassinate anyone who might time travel in hopes of stopping future problems.

They attempted to steal back the plutonium because they feared it was the origin of the hydrogen bomb used on the island by the time travelers in 1977. Because the Others hid Jughead underground, DHARMA never knew where it came from, and thus assumed future time travelers Marty and Doc were the source of the nuclear material.

The only problem is the Celebrity Paradox: Back to the Future exists in Lost's universe; one episode has Hurley checking his hand to see if he's disappearing and he references the franchise's time travel rules.

At some point between reacting to the "new" 1985 and arriving in 2015, Marty's memories and personality change to fit the new version of history.

In the first movie, Marty has self-esteem issues so bad, he won't send his demo tape to a record producer in case they don't like it. Second-movie Marty automatically assumes he's going to be a famous rock star. This discrepancy is because second-movie Marty was influenced by a father who was a successful author, not one who never sent his book to a publisher for exactly the same reason Marty wouldn't send his demo tape. The new Marty's improved self-image has a downside, however: that sensitivity to being called "chicken."

This would also explain why Doc and Marty acted as though the new 1985 was the "correct" timeline throughout Part II. It just took a while for the Delayed Ripple Effect to get to Marty's memories.

It may also explain where Marty's weakness to the word "chicken" came from. Something may have happened exclusively in the new timeline to cause his disposition, explaining why this was absent from the first film.

To be fair, it was the correct timeline for Doc. Only Marty traveled back in time at that point.

Perhaps it's the same incident which made Needles his arch-nemesis who was never mentioned in the first film?

It also explains why the new 1985 is a good thing rather than the Fridge Horror of your family of 17 years having different personalities and histories—eventually, Marty acclimated to those changes as his new memories caught up.

Second-movie!"1955"!Marty is taking part in what appears to him as a Stable Time Loop. The ripple effect went round and round until it found an equilibrium.

The McFly family is somewhat inbred.

Marty's paternal great-great-grandmother Maggie looks just like his mother because both are played by Lea Thompson. George and Lorraine are second cousins, although they are unaware of it.

Marty and the Doc are the same person.

The Doc never seems to age visibly; could he perhaps be an older (much older) version of Marty who has come across or invented some kind of rejuvenation treatment?

In Part III, Doc tells Marty a bit about his childhood, which would be pointless if they were the same person. Marty doesn't seem like the type of kid who would be enthralled by Jules Verne anyway. Furthermore, the Doc briefly touches on his family's history in the same movie, and he mentioned in the first film that it took his entire family fortune to build the time machine; therefore, he definitely has a background.

It is established in film continuity that Doc Brown is very against letting your earlier self become aware that you are their later self! He'd lie to Marty about their being the same person to preserve the universe.

We see the Jules Verne bits when he's with Clara. He has no reason to lie to her.

Women talk, man. Clara could accidentally let something slip to Marty. Either that, or Doc replaced his real memories as of being Marty McFly with false memories of a past as Emmett Brown to completely make himself a different person as seen below.

Doc is visibly younger in 1955 than in 1985 in the first movie. After going to the future, he got a rejuvenation that allowed Christopher Lloyd to play 1985-Doc without heavy age makeup. They also replaced his spleen and colon. Granted, at the end of Part 3 about ten years have passed for Doc, but maybe rejuvenation slows senescence.

Okay, what are you smoking what version of the film did you watch?

The one where Doc in part II wears a Latex Perfection mask to avoid giving away his age— and when he pulls it off looks exactly the same as he does in all three films.

Marty went further into the future to not only get a rejuvenation, but to have his brain genetically enhanced to make himself a genius— a side-effect was that it altered his personality. Before he went back and became Doc, he used his new intelligence to realize the damage he was doing to the timestream, and he had his memory erased or altered just before going back; he then remembered/"invented" the time machine.

Does it even need to be stated that the Telltale games Joss this three ways 'til Thursday?

Old Biff's reason for choosing November 12, 1955:

When Old Biff gave the Timeline-Altering MacGuffin to his younger self on the date of the lightning storm, it was no coincidence. Biff chose that date because he believed that that day was the day that his entire life changed. And it was. Getting decked by George turned him from a bully into a relatively nice guy a wimp afraid of his former victim. Old Biff decided that that life sucked, and he still had a grudge against George McFly, and so he went back to the moment that things changed.

There's a deleted scene from Part II where the Clock Tower Guy in 2015, Terry, reminds Old Biff of the date while shaking Marty down for money. Terry was the mechanic who told Biff it was 300 bucks for getting all that manure out of his car. Probably hearing about the manure helped remind Old Biff of all the other stuff, so yeah. Off to November 12th!

That's the only date where Old Biff can remember exactly where he would have been in the past, so he knew he would be able to find himself.

In The Sims, Sunset Valley/Pleasantview (the main setting of TS3 was founded by Gunther Goth, who is middle-aged in The Sims 3, the chronologicaly first game in the series. Hill Valley was founded in the year 1850 in BTTF, so that is impossible.

Sure, THAT'S what's impossible, in a shared universe in which physical time travel is possible via a sports car.

Seamus and Maggie McFly are Lorraine's great-grandparents, not George's.

The surname is just a coincidence. One of them looks like Lorraine, the other looks like Marty — not George, Marty. Marty didn't get his looks from his father's side, but from his mother's. (When you think about it, he looks more like her anyway.) This also explains why George and Lorraine are still happily married despite the implications of her having a son who looks exactly like her high-school boyfriend Calvin. She has photographic proof that that face runs in her family.

It makes more sense that George has photographic proof that Marty's face runs in HIS family.

See also the inbreeding theory above.

Of course, there is William "good-looking guy" McFly.

Utterly and thoroughly Jossed in the Telltale games, where we meet an adult William and Arthur McFly; the former indicates that Seamus was his father and Arthur is his son. And George indicates that Arthur was his father (which, given that he's an Identical Son, didn't really need to be stated, but still...)

Doc got the time machine from the future.

He came up with the Flux Capacitor concept when he hit his head on the sink and was unconscious, right? Well, maybe Future!Doc (or someone) came back and implanted the idea in his head using future neural technology, or old-fashioned hypnosis? The time machine has no origin, it just keeps going around and around...

Facepalm BTTF is not a Stable Time Loop, as proven by all the changes like George's assertiveness. And even "Johnny B. Goode" is a terrible example because Chuck did not hear anywhere near enough of the song to have stolen it, and Marvin had no opportunity to memorise the lyrics he did hear.

Consider that by the time Part III happened, Doc learned that the Flux Capacitor could actually work, he'd already had a week to study the original time machine, and even rebuilt the Time Circuit Control microchip with 1955 components. All that he really needed was to wait until 1981 (When the De Lorean DMC-12 was released) to start building it.

Marty's daughter is transgender

Yeah, Michael J. Fox played the part, but seriously, what woman has gams like that? It's never brought up on-screen because, well, it's the future, and such things are no longer an issue.

Marty's kids are identical twins with one of them being transgender. The reason Marty is accepting of his kid being transgender is partially due to Doc blurting out to 1985 Marty about having a daughter.

"it's the future"?? The "future" of Back to the Future is only a shade over 3 years from now. (Feel old yet?)

He looks (and sort of sounds) like he's played by Samuel L. Jackson, but he was played by Al White. Instead, the character (only listed as "Dad") is Samuel L. Jackson.

One of the effects of 1985-A is that Samuel L. Jackson's movie career was unsuccessful, probably due to Biff's influence over Hollywood. We know that Biff lobbied in the state capitol and was helping Richard Nixon get elected to a fifth term in office; it's reasonable that he also had some sway in Hollywood. Thus, Samuel L. Jackson settled into a quiet suburban life in Hill Valley.

I always thought it was Goldie Wilson, who never got to be mayor due to Biff's influence.

There is a lot of crime, and Nixon is president. And it would be cool.

You think a being like Dr. Manhattan wouldn't have something to say about a figure like Biff using an object clearly not meant to be present in this stage in time?

It may have something to do with Doc M being created some four years after Biff changed the future.

But, the headline in 1985-A shows that the Vietnam War was still going on until at least 1983. Whereas in Watchmen, the war was resolved with a quick victory for America.

Could be a different Vietnam War. In Watchmen, the US and Russia are implied to have extremely aggressive militaries.

Doc's family did change their name some time in the past, but in one timeline it became Brown, in another it was Osterman. The split occurred when Manhattan went back and caused his family to settle in California instead of New York, in hopes of preventing his father from becoming a watchmaker.

Marty jumped to his death during 1985-A

When Biff traps Marty on the roof, Doc seems to be waiting for him rather conveniently. It seems likely that Marty died in one timeline, and then Doc heard about it and went back to save him.

No, because Marty was expecting Doc to be waiting at the roof edge in the DeLorean in the first place — when he hits the edge in anger after looking down it's not because of the height or lack of fire escape but because Doc isn't there. It's set up in the scene where Marty confronts Biff in the jacuzzi, when Biff asks "How did you get past my security downstairs?": Marty bypassed them completely by being dropped off on the roof by Doc. So it wasn't "convenient" that Doc was there — Marty just had to wait for Doc to fly back before he could escape.

At some point, the time machine goes back to when Earth had just formed. Doc (or possibly Biff), unable to breathe, quickly returns to the human era, but leave behind some bacteria, which go on to evolve into everything else.

But it can't go back before year zero. There's no "BC/BCE" switch. And it can only do four-digit years anyway.

It can only display four-digit years and zeroes on the dashboard. Doesn't mean it can't actually travel that far.

Set the display to -4E9. Problem solved.

Still suffered from the Ontological Paradox.

Wait, you're saying we are all decendants of Biff?!

Twin Pine George was hit by Lone Pine Marty, not by the car that hit Twin Pine Marty.

The Twin Pine version of the same car hit Lone Pine Marty, and Lorraine went all (misnomer-version) Florence Nightingale Effect. Instead of trying to get them together in a different way like Twin Pine Marty, LP Marty sets up a Tricked Out Time "Loop" (as far as he knows, and for real assuming this is the case, a Tricked OutTimeLoop) the direct way by stealing a car and running it into George. Since he's used to driving, unlike Twin Pine Marty, he expects to be able to stop in time to avoid severely injuring George (whether he manages to compensate for the lack of power brakes and difference in density or if his inability to compensate causes George to be injured enough that Lorraine forgets about Marty for him is up to individual opinion).

Note: this theory is dependent on LP Marty being more resistant to Ret Gone than Twin Pine Marty, since he has to get to the clock tower moment with neither his parents meeting nor his getting too immaterial to drive to pull this off. Fortunately, that is already practically canon, seeing as he or another version of him lives through those exact events trying to protect Twin Pine Marty in Back to the Future Part II and doesn't appear to fade out...

George thought he had been visited by a devil, and with proof that Hell exists, was more interested in living a full, enjoyable life with maybe a little pain than living an empty life followed by possibly being toasted on a spit for all eternity thanks to some Deal with the Devil he might have accidentally made.

Dark Father from the planet of the fire god? I know Vulcan's the god of smithing, but that gives him dominion over forge fire and his name's in vulcanization and volcanoes. Punching Biff was keeping himself from committing a sin of omission, and publishing his novel was to make his years on earth more enjoyable since Heaven would become better (less stressful than life) and he might at least get some enjoyment out of life in case that's not where he went.

George figured out that "Calvin Klein" was a time-traveler, and eventually who he actually was

What a strange thing to say - but then, "Calvin" might have just thought he was a musical visionary.

However, "Darth Vader from the planet Vulcan" left an indelible impression on George (judging by the cover art of his book, assuming you can). A SF geek would have avidly watched Star Trek during its initial run, and the evening of November 17, 1967 probably didn't pass without poor George yelping at the Vulcan salute. While he did tell Calvin about the event, an angry George would have easily found out that no "Calvin Klein" wrote for Paramount - and more research would have found out that the writer didn't know any Calvin Klein and had never heard of his experience. In fact, research wouldn't have turned up anything about a Calvin Klein who went to his school - just a rising fashion designer who looked nothing like his old friend.

Add to those details all the many little oddities of Calvin's behavior (and his weird "life preserver" outfit when he first arrived), and it would be a very small leap for George to realize that Calvin was from the future - and that he had probably been the "masked alien", as both of them had been very concerned about him getting together with Lorraine. 1977 would have clinched it if George had any doubt. Further pondering about just who would travel through time and care so much about him ending up with a particular girl would lead George to the conclusion that Calvin had to be a descendant of George and Lorraine.

Would he remember the "Dad...uh, daddy-o," slip? Would he dig up his old yearbook and see a picture of his son playing at the dance? Or would he just look at Marty one day and realize that Calvin had been a very immediate descendant of his?

Either way, he'd probably never tell Lorraine, if it could be avoided. That'd just be weird for her.

This also explains why he never brought it up. If he actually asked Lorraine on information about Calvin, she'd point him right in the direction of Doc Brown, who would probably tell George not to talk to Marty about it until October 27, 1985, lest it cause a temporal paradox.

If I remember correctly, this was actually how the first movie ended in the first draft script (before being replaced by the "something's gotta be done about your kids!" cliffhanger). George sits down at his desk, and on impulse opens up a scrapbook containing a newspaper clipping about the dance, including a picture. He looks at the photo showing "Calvin" playing on stage, and he frowns slightly and says "No... couldn't be..."

This is the most brilliant idea I've ever heard of in my entire life. I've stolen the idea, re-written and extrapolated from it.

As an avid sci-fi fan, after the premiere of "Star Trek", George McFly must have been distressed remembering his visit by someone from the planet Vulcan. Granted he may have been too disturbed by the guitar riffs melting his brain to retain the "live long and prosper" sign, but the fanbase and questioning Paramount doesn't reveal anyone named "Calvin Klein" connected with the show.

Then in 1977, he saw "Star Wars", whose main villain had the same name of the strange visitor he'd had back in 1955. What motive could Darth Vader have possibly had to set him up with Lorraine? When he asks Lorraine, all she knows is that Calvin was staying with that crazy scientist. She may even have mentioned how she knew his name was Calvin Klein, an up-and-coming fashion designer who looks nothing like his old high school chum.

Remember, George is an avid sci-fi fan, *and* a creative writer. Is it really too big a leap to suspect he might have figured out most of the truth on his own? Especially once his son Marty (born during the third season of "Star Trek", being 17 years old in 1985) shows an interest in skateboarding and playing guitar. Lorraine always wanted a kid named "Marty", and his sudden best friend in high school was obsessed with hooking the two of them up, just like Darth Vader. The more George looks at it, the more logical it gets. His son travelled through time. He doesn't know how or why, but a visit with Doc Brown might help. Just to, you know, discuss ideas for his next novel about an alien visitor sparking a love story.

We'll never know what Doc told him. He may have revealed as much as he could - cautioning that no one should know too much about their future - or clammed up entirely. My guess is the truth is somewhere in-between. George related his experience with Darth Vader from the planet Vulcan - Doc was presumably a fan of those series as well - to inquire about alien visitations, and Doc realized that George *knew* something.

It's likely that this encounter returned Doc's attention to that 'flux capacitor' idea from decades before. Realizing that he couldn't jeopardize the space-time continuum by working on other projects, he devoted himself towards the serious task of obtaining plutonium, which showed no signs of being available in corner drugstores anytime soon. This is also when he reconstructed the letter Marty had written.

He did tear the letter up, but obviously wouldn't throw it away. Why would he dispose of a souvenir written by the first time-traveler, in a machine Doc invented? Also, by the time of George's visit, time is getting short and whatever time travel research Doc has conducted since 1955 has demonstrated that the risks are less. There's also the 'what the hell?' factor. My guess is he kept every scrap of paper, so that on the night Marty went back in time, they would be able to discuss the letter and Doc could calculate the ramifications; he was wistful about having to wait thirty years to be able to discuss the last week.

It's possible that reconstructing the letter, discovering that he would be shot and killed, is what led him to the Libyans in the first place as a source for plutonium. Legitimate sources would want the benefits of his research, all he needs to do is find people who will kill him and figure out how to survive the encounter. But then, if you put your mind to it, you can accomplish anything, something he probably repeated to George during their interview. George wasn't paying much attention when Marty said it, so it's unlikely to have become a McFly family saying without reinforcement.

Marty actually DESTROYED Goldie Wilson's political career

Goldie managed to go from being a '50s black cleaning boy nobody gave a * beep* to Hill Valley's mayor in 30 years despite not studying when he was young, all by himself. Evidently, this convinced Goldie that he was able to achieve anything he wanted in his life, so he viewed the city hall as just a step before running for state governor and then US president.

Marty's intervention changed it. By travelling to 1955 and telling Goldie he would be mayor, he convinced Goldie he could only be mayor, something his 1955 self definitely saw as an ultimate goal in itself, but his (original) 1985 self wouldn't. The result was a Goldie actually less ambitious, that only aimed to be mayor and sticked in this charge once he achieved it, refusing to run for some higher post and failing to impress his issue into pursuing further political careers. From then on his descendants aimed lower and lower until Goldie's grandson came to feel himself fulfilled despite being just an used car salesman. Thus Marty destroyed both the apparition of an early Obama on the political stage and the emergence of a Black Kennedy-esque dynasty in Washington DC from the 90s onward.

No, in 2015, Goldie Wilson III isn't quite old enough to be mayor, he's young like Goldie Wilson was in 1955. Also, Goldie Wilson III isn't a used-car salesman, he hover-converts older cars.

Indeed, if you look in the background of the 2015 scenes, there are signs that read "Re-Elect Mayor Goldie Wilson Jr."

From 1 BC to 1000 BC, the DeLorean just subtracts one from the absolute value of the year's number and adds a - in the first digit space.

Doc doesn't know ancient Egyptian, Greek, Babylonian, or any other language in its form from 999 BC or earlier, and he'd look as out of place there as he would in pre-White Man Cometh Aztec culture, and he really only cares about getting cool tech from the reasonably near future and going to the old west, so why bother putting an extra digit in just so you can risk giving a modern, virulent disease that we've adapted to to the direct ancestors of some tenth of humanity?

Alternately, the readout could just turn a different color when in the range of BCE years.

Doc and Clara had been traveling with Marty for years before they picked him up at the train crossing.

Marty fading in the original film wasn't him being Ret Gone, it was just him being transferred back to the original timeline.

This also explains the difference between FirstMovie!Marty and SecondMovie!Marty pointed out in the "Changed To Fit The New Timeline" WMG above— between films, the original and "new timeline" Marties exchanged places, going back to their respective universes.

Those weren't laserdiscs discarded in the alley in 2015; those were DVDs.

The future we live in now is the final result of all the time meddling through the three films.

The future of 2015 that Marty visited was only the result of the time continuum created by the events of the first movie. The results of the third movie are this time continuum we see today, so now, in 2010, there's no hope of hoverboards or flying cars or self-drying jackets or Mr. Fusion devices being developed in the next five years. Nice Job Breaking It, Hero!

This would ultimately result in paradoxes. The DeLorean would never have had a hover conversion, and Doc would have never saved Clara from certain death using the hoverboard. And we wouldn't see the flying train at the end of Part III. Meaning...

The BTTF universe takes place in a parallel universe to our own.

As far as we can tell, the real world and the BTTF world were pretty much identical pop culturally and technologically until at least 1985. Despite the open-endedness of Part III, Doc's train still has a hover conversion, and Jennifer still has that sheet of fax paper from 2015 (albeit a blank one, but bear with me), meaning that BTTF's 2015 still happens much of the same way, hover conversions and all (except that Marty is likely a successful musician).

That's not to say that BTTF's future is completely different from ours. Hover tech notwithstanding, perhaps BTTF's future is aware of things like House, Futurama, Harry Potter, the iPhone, and the Internet—all slightly different, of course, and all of which go unmentioned in the film for obvious reasons. (Heck, you could even argue that the likes of Lady Gaga or La Roux had a more lasting impact on the weird fashion sense of the BTTF future than in ours—just go watch the video for "Bulletproof" and compare the singer's look to some of the people in Part II.)

Speed for time travel is arbitrary based on the traveller's preferences.

For the first test at Twin Pines, Doc sets the speed for 88 mph to show off a bit to Marty ("...yer gonna see some serious shit!"); but the speed remains set at 88 when Marty accidentally jumps back to 1955. However, when Doc first departs for 2015 after dropping Marty off at the end of the film, the time machine definitely does NOT appear to be going 88, meaning Doc must have reset his temporal displacement activation speed (maybe as a safety precaution). That's what the the seemingly useless buttons and doodads on the DeLorean's ceiling are for, as Doc punches them at the end of Part I right before the car flies away. He sure didn't appear to be going 88 when he reentered 1985, and perhaps he reset it to 88 to be a showoff to Marty and Jennifer.

However, the arbitrary speed settings were damaged with the time control microchip when the car was struck by lightning in Part II. The replacement transistors and tubes from 1955 didn't have the speed settings that the microchip had, binding the time machine to the 88 mph needed for time travel, leading to the problem in Part III.note Notice that with the control tubes in place, the car starts sparking WAAAAY before Marty hits 88, very much unlike when the car had a microchip, when it only sparked at the set temporal displacement speed.

Word of God has it that the car jumped at the end of II because the shock wave from the lightning knocked it into a loop (hence the fiery trails looking like a double six).

Our timeline is the result of another time traveller messing with time.

Even though we already have some rudimentary form of flying car and hoverboard, by 2015 they will not be as advanced and ubiquitous as they were depicted to be in BTTF2. On the other hand, information technology marched much faster than what was shown in BTTF2, and pretty much every electronic device we have can be connected to the internet (which was implied not to exist in BTTF2). This is because another time traveller used his own time machine to change the timeline for his own purposes (just stealing the Delorean for it would result in a time paradox, because it is equipped with technology from a future this action would cause not to exist). More precisely, he went back to 1989 and invented the World Wide Web as Tim Berners-Lee. This caused information technology to progress with unnatural speed, while at the same time slowing down to a crawl every other sector of technology.

Corollary to the previous WMG: if a BTTF4 ever gets made, this is what it will be about.

Doc, when he was in 2015 the first time, accidently interfered with the timeline

This caused Marty, Jr. and his sister to get in trouble and jailed. Think about it, Doc is FANATICALLY opposed to any tampering with time even if it does spare suffering. He won't reveal to Marty the nature of his "accident in the future", yet Doc seems DETERMINED to interfere with the future timeline and spare Marty's children any suffering.

Time-travelling has caused many alternate and canon timelines.

Meaning that every fanfic about the series can be true, including "Morty Mcfli"'s cameo in My Immortal.

Before his first trip to 2015, Doc had an undiagnosed cancer.

He says he got his colon and spleen replaced and his blood changed, and that treatment added 30 to 40 years to his life. Now, why would that treatment extend his life so much? The answer is: Doc used to have a colon tumor (more common in old people) that metastatized to his spleen, so the future doctors had to replace those organs to remove the tumoral masses. And they changed his blood to flush out the remaining tumoral cells that circulated through his body.

The 47-year-old Marty was one of the "tranqs" the two cops were talking about.

Assuming "tranqs" are people who are addicted to tranquillizers.
Evidence: he activates "lithium mode" on a panel, and lithium being used as a tranquillizer is Truth in Television. The lithium mode he activated was probably lithium being added to their drinking water, which is what psychiatrist Peter Kramer proposed in reality in 2009 to reduce suicide rates.

And 47-year-old Marty is pretty depressed.

In a deleted scene, Old!Marty discoveres Old!Jennifer passed out (after encountering her younger self). He mutters "She's tranqed again...". So at least one member of the household is tranqing.

Another possibility is that "Lithium" reffers to batteries. The Lithium Ion batteries we use to day wheren't around in The '80s, but where known to be theoretically possible, hence a "Sci-Fi" technology at the time. "Lithium mode" means that he has the house running on batteries rather than the grid to save money. Obviously the "damned kids" would switch to grid mode so they could have more power to use their electronics. Basically a "Sci-Fi" twist on the classic "damn kids running up the power bill!" problem many fathers have to deal with.

The timeline would've corrected itself

Biff comes back out of the time machine in 2015 and disappears, but the neighborhood doesn't. Hilldale, for instance, was built in 1985 as a nice neighborhood. In 1985-A, it wouldn't have been built altogether. Furthermore, if Doc was committed, he would never have built the time machine, and never allowed Biff the opportunity. Marty and Doc were destined to succeed at saving the future.

If Doc was committed, he would never have built the time machine, and never allowed Biff the opportunity. So he would have never changed the timeline and Doc would have succeeded in building the time machine and allowed Biff to travel to the past, causing Doc to be committed... and so on. This is what the movies call a paradox.

That, however, is based on the unspoken assumption that the events would play out exactly the same way in every iteration of the timeline. There's no reason to assume that that would be the case. It could be that the "paradox" would simply be a recursive correcting agent, replaying the events over and over, slightly different each time, until a consistent timeline unfolded.

The stock De Lorean takes 10.6 seconds to get from 0 to 60 MPH, and 40 seconds plus a LOT of room to get up to 100. Doc had to include a lead-lined chamber for the plutonium, which must have added significantly to the car's weight. With the stock engine and that much extra bulk, it might not even have been able to reach 88 MPH at all. So he replaced it with a much more powerful engine from a sports car. That explains why the engine noises don't match those from a normal De Lorean.

In the original timeline, Chuck Berry didn't write "Johnny B. Goode"

All Marty says is that was an oldie where he comes from. Perhaps in the original timeline, it was a different artist's song, which Marty then gave Chuck Berry the idea for.

We live in the "alternative" time line, i.e. the one in which Chuck Berry "wrote" Johnny B. Goode and George is successful.

Biff decided to enter the auto detailing business because of the 1955 manure crash

We saw how outraged Biff was to be charged $300 to clean and detail his car after crashing into the manure truck in 1955. (Running that through an inflation calculator, it comes to over $2,300 in today's currency - no wonder he was so angry!) Obviously this experience stuck in his mind for a long time (he still remembers it when he travels back from 2015) and the fact that it was so expensive gave Biff the idea that detailing and repairing cars was a good way to make money.

Especially because Biff had to have the car cleaned twice in the same week. And the detailer probably charged even more for the second time for Biff's stupidity.

Biff probably had to do it himself the second time around (because he was out of money!) and that's what set him down the path to auto detailing.

Griff's gang in 2015 is made up of the grandkids of Biff's 1955 gang

Spike (the girl in Griff's gang) even has a slight physical resemblance to Biff's lackey Skinhead ("get a load of this guy's life preserver").

Any of them. Biff's gang (and Biff himself) would have been exactly the right age to serve in The Vietnam War, so it's certainly possible one of them came back with a Vietnamese wife, and if his kid married an Asian-American he could have easily ended up with an Asian looking grandson.

Biff was born in March 1937 (just subtract 21 years from the 'Hill Valley Man Wins Big at Races' headline date to calculate this). Therefore, he most likely would have been too old to fight in Vietnam and too young for WWII, but he could have fought in the Korean War.

Too old to be in the thick of Vietnam, yes, but the right age to be a ranking officer, yes.

But the Korean War went from 1950 to the armistice in 1953, so he'd still be too young.

US troops have been stationed in Korea since then. He could've easily served a tour of duty there during peacetime.

Or hooked up with any of the many women of East Asian descent already in the US without finding a war.

On that matter, Needles' 1985 gang in Part III are probably made up of the descendants of the Tannen gang members throughout the trilogy. Needles' gang members were played by a member of each Tannen gang: J.J. Cohen, who was Skinhead in Biff's 1955 and 1985-A gang in Part I and II, could be Skinhead's son. Ricky Dean Logan, who was Data in Griff's 2015 gang in Part II, could be Data's father. And Christopher Wynne, who was part of Buford's 1885 gang in Part III, could be his great-great-grandson.

Biff didn't have anything to do with Doc's institutionalization in the "Hell Valley" timeline

Even though Old Biff warns Young Biff about "a kid or crazy, wide-eyed scientist" when he gives him the Timeline-Altering MacGuffin, Doc actually went insane because of his inability to understand why the timeline was deviating so much from what Marty told him. Doc would be the only one in the know about how certain future events are meant to unfold.

When Doc Brown and family visit Marty and Jennifer at the end of Part 3, Doc originally intended to destroy the Delorean and, if necessary, kill Marty.

He had not foreseen that the train would destroy the flux capacitor, and, knowing Marty's irresponsible nature, predicted Marty would sell the technology. Not able to bring himself to harm Marty, he put it off, knowing he could always go back and do it later. But just in case it didn't come to that, he prepared the 1885 photograph to give to Marty as a gift.

...not to come off as an ass, but I'm pretty sure Doc wouldn't partake in killing his best friend. Now, the idea that Marty would sell the technology is feasible, but I think that Doc knows that, considering how Marty essentially screwed over 1985 in "BTTF Part 2" with the sports almanac, which ended up in Old Biff's hands, Marty wouldn't do anything so stupid. Also, it was asked in Doc's letter from 1885 that when Marty returned back to 1985, he would DESTROY the time machine, and Marty (until it was revealed that Doc DIED in 1885) would honor his friend's wish. But then he had to go back to 1885 to get Doc, and he saw first hand that, thanks to the laws of time travel or some bull-honkey, Doc had his chance at love crushed. So, with Doc decided to, out of grief, reinstate his desire to destroy the time machine, Marty would go along with it for his firend's sake. ...sorry about that rambling there. Bottom line, I don't think Doc would even CONSIDER killing Marty.

Why would Doc take Clara and his sons on a mission to murder Marty? Not only would it be emotionally traumatizing, especially for the children—seeing their father kill someone and seeing what the future has in store, Doc knows from experience how easily things can go wrong in the future. That he's taking his wife and sons around in time like it's a vacation is probably evidence that he doesn't care about timelines getting crossed any more, not that he wants to keep them in strict order.

Not to mention, if he cared about the timeline enough to kill Marty to keep it pure, he wouldn't have married Clara and had Jules and Verne. He'd have thrown her off a cliff. She's even more of a threat to the timeline than Marty.

After Marty went into the future and never came back, Doc decided he would rather escape than risk being arrested for life. He creates a spaceship (hey, he built a time machine, so how come he couldn't manage that?) and just so happens to crash into the Past version of Little Planet as he's passing over Mobius. He develops new and fantastic inventions in his laboratory (Wacky Workbench), including a version of the time machine that can operate at lower speeds and without need of a car to do it. A long while after Doc died, Robotnik found Doc's stockpile of time machines in Wacky Workbench (in the present) and decided to use them to take over Little Planet. That secret statue in Wacky Workbench Past that gives you rings? It's Doc's grave.

Needles is Biff's estranged son.

Because come on, every Tannen has a beef with a McFly in every timeline EXCEPT the present one. Needles is just Biff's son from a woman that's no longer with Biff. So he has a different last name and doesn't associate with his Father until he has a son of his own, which he names Griff as a nod to his Father that he accepts him into his family.

Jossed further in Episode 4 by a reference to Mr. Needleman (probably Needles' grandfather), whose mind map suggests him becoming a hooligan.

Unless Needles was born out of wedlock and Needleman is his mother's surname.

Jennifer looking different in Part 3 is a side effect of the timeline getting changed around.

While Marty's parents presumably conceived their children at the same or similar time as the previous timeline, Jennifer's parents conceived her at a different point, resulting in the egg being fertilized by a different sperm; the child was still female but looked different.

Doc Brown murdered Lone Pine Marty.

Doc Brown had met Twin Pines Marty and had his letter explaining what would happen. He knew sending the new, spoiled rich-kid Lone Pine Marty back into the past risked messing up the time-stream even more. Therefore, he rigged the car Lone Pine Marty drove in some way, probably to take that Marty to an isolated time period and explode. That second Marty seems to drop off the face of the Earth. There's no indication in the second movie that the Marty seen in the past isn't the original Twin Pines Marty.

Griff is the illegitimate son of Biff's daughter Tiff, who is mentioned in the Telltale game.

This would explain Griff's surname.

Or Tiff kept her original surname when she got married. That does happen.

Technically nobody ever mentions Griff's surname. Doc just calls him "a guy named Griff." The credits do identify him as Griff Tannen though.

When 1955!Doc asked Marty whether something had happened to the Earth's gravitational pull by 1985, he was just being sarcastic.

If some punk kid from thirty years in the future showed up on my doorstep and repeatedly used obnoxious future-slang (e.g., "this is heavy") at me, you'd better believe I'd call him out on it.

But you can't possibly know what is considered slang from a different time, especially a future one. If someone from the future actually did come here to The Present, one could likely use words we've never even heard of before. Something like, "Boy, you get really skronlist in the future. Don't stinop so much." It just so happened that the times weren't far enough apart to cause too much confusion. But, rest assured that people from different times do talk completely differently, so I highly doubt that Doc wasn't being serious when Marty implied gravity fluctuations in the future.

Marty is very vain about his teeth.

He refuses to eat anything with sugar and in 1885, members of Mad Dog's gang mentions that he never saw teeth that white and straight that weren't "store bought". Could be Marty had braces when he was younger and now prides himself on having very nice teeth.

The refusing to eat sugar could be typical teenager watching his weight, hence why he's drinking Tab in 1985 and asks for Pepsi Free in 1955. And in the late 1800s quality dental care was unheard of.

Alternately...

Marty has mild type II diabetes.

His family circa 1985-A can't afford to treat it/their insurance won't cover it, so he has to be extremely careful to avoid sugar (which he does) and get lots of regular exercise (considering how much running/jumping/skateboarding, etc, he keeps up on that too) in order to hold off the need for insulin and lower the chances of complications. In 1985-B, his family is simply better off and could afford better medical care for him to begin with, so he's less concerned about his diet (Hence being totally cool with eating a rabbit full of buckshot).

But when Marty is seen talking to George the day after he breaks into his house disguised as "Darth Vader from Planet Vulcan", he's seen drinking regular Pepsi, which has sugar in it.

Maybe Doc found out Marty had diabetes, and keeps insulin around the lab just in case, and there's some in the glove box of the Delorian.

Marty was always sensitive to being called "chicken".

He was just never called it in the first film.

Although when Lorraine accused him of being "square" for objecting to her drinking he took a drink from the liquor, so that could be a very subtle example.

And bearing in mind that he saw George as a complete wimp in the first timeline - being called "chicken" meant being compared to his father.

2015 is a dystopia.

Marty's son is sentenced to fifteen years prison two hours after he's arrested. Why? The justice system moves faster because all the lawyers have been eliminated.

Lawyers serve a very important role in the legal system. Removing them is pretty much asking for trouble. It was probably a throwaway gag, but it certainly doesn't help given the Cyberpunk/The Future Is Noir feel the rest of 2015 has.

The dog statue on alternate 1986's City Hall aren't of Einstein.

They're of Copernicus, who he owned briefly in the fifties or thereabouts until Edna found out about him.

The Bttf Trilogy represents the themes of the first three Metal Gear Solid games.

The main theme of the first installment of each trilogy is GENE. The impetus for most of Marty's actions in the first movie is to cause his parents to marry once again, causing him to come into existence from their genes. Likewise, the second movie matches with Metal Gear Solid 2's main theme of MEME. The consequences of information from the future traveling backwards are expanded upon and shown in detail, as Biff uses the Sports Almanac to change his past and eventually 1985. Finally, the third movie fits with Metal Gear Solid 3's main theme of SCENE, since it puts the main characters in a completely different setting than any of the movies offered, and shows how that affects the other characters' outlooks. It's also like the third game in that it shows familiar character-analogues and recurring series events in a historically earlier context.

Certain aspects of time itself is sentient and can affect timelines, and it likes both Martin and Doc.

The reason Marty and Doc have time traveled several times without screwing up enough to make any fatal paradoxes is because the sentient parts of time has grown to like them both, and cleans up parts of time to help them out. The fact that the McFly family suddenly becomes awesome, and that Doc eventually found the love of his life, was little gifts from time itself. And the reason they often get into trouble (lightning bolt hitting the De Lorean much? Biff going back in time?) is time wanting to get them into adventures both for its own amusement and them getting amazing memories.

Lorraine has an interesting way of meeting boyfriends...

When Lorraine's father (Marty's grandfather) hits Marty with the car, he complains that "another" teenager threw himself in front of the car. This has happened before. Lorraine met all of her previous boyfriends because they were trying to look through at her through her bedroom window and got hit by her father's car. This also helps explain why Lorraine is so taken with Marty: she assumes he was looking at her as she dressed (and apparently she doesn't find this creepy; maybe she even sets it up on purpose) and therefore she assumes that Marty is already attracted to her. In fact...we can further suppose that Lorraine's father suspects that this is the case. Therefore, he tends to hit these boys with his car on purpose (not too hard, mind you) as a way of saying "stop being a peeping tom". He further acts cold towards Marty at the dinner table, because he thinks Marty was peeping.

Relatedly, just as Marty is leaving Lorraine happens to say "Marty...that's a nice name", which presumably inspires her to name her son Marty. But she named her first son Dave instead. Why? Because Dave was the name of her first boyfriend who she met due to her father hitting him with the car. Marty was next on the list.

By the end of "Double Visions", everything will be fixed.

It's simple logic, really: The promo at the end of "Citizen Brown" shows that Citizen Brown might've resisted the mind control. And this had to have happened, because another chunk of the trailer shows that at least Marty (although in non-period accurate clothing) got to 1931, meaning the DeLorean was fixed.. Besides, it seems the only two problems left are making sure 1931!Doc and Edna break up AND that 1931!Doc has that "spectacular failure" at the Hill Valley Expo". Therefore, there's a chance that everything will be corrected by the end of episode 4.

...What? I forgot about episode 5? Well, that one is simple too; you see...

"OUTATIME" will be about Doc and Marty trying to get back to 1986 in a malfunctioning DeLorean.

The only two pieces of evidence I can give to support this are two minor things and one Fridge Logic thing. Both minor things come from "It's About Time": First, we have the fact that the only thing preventing Marty to save Doc right away once the DeLorean appears is that the "Last Time Departed" bar on the time circut readout is spazzing out. The second minor thing is that once Marty does get to 1931, the readout takes longer than usual to update itself, where it changes exactly when Officer Danny Parker begins shooting the DeLorean.

Then comes the Fridge Logic thing: in order for Marty and Citizen Brown to fix the timeline in "Double Visions", Brown needs to fix the DeLorean. Using materials at his disposal. ...which means that the repairs he made to the DeLorean will no longer exist once the timeline is repaired, so... you see where I'm going with this?

This depends on what those modifications count as. Inanimate objects carried through time are never erased by the alteration of history, only modified. If the modifications count as their own objects, they will survive the prevention of the dystopian 1986, but if they count as being part of the Delorean, they're on the same level as people in a photo, so it's glitch time.

And where will our intrepid heroes go? Well, with the time circuits going berzerk, the Delorean wouldn't be confined from the measly range of 0 to 9999 AD. A crossover with Telltale's upcoming Jurassic Park game may occur, courtesy of the actual Jurassic Period (continental drift notwithstanding). And, of course, as hinted in Episode 1, 2011 may also be on the cards.

Yeah, um... considering how my prediction for "Double Visions" is now Jossed, there's a good chance this is too.

The DeLorean is destroyed/wrecked in every third installment.

This is more of a weird idea I had. Concider. "Back to the Future Part III"? The DeLorean was destroyed by the train. "Citizen Brown", the third episode of the Telltale game? The DeLorean A) crashed through a billboard, apparently getting wrecked (pointing your cursor over it at the start of the game has it labeled "Wrecked DeLorean", B) had it's window broken and C) fell from said billboard, andcrashed into the ground! Now, maybe it's just me, but I smell something fishy here...

Which leads to the obvious corollary, or whatever: The fourth installment sees the restoration of the DeLorean. The obvious examples are:

The Doc set an explosive on a timer in his blacksmith shop so no one would learn any new technologies from it.

But, after saving Clara they got back right in time to defuse the bomb and get to work on their time machine.

Clara, building on Doc's explanation of the time travel circuit, was the one who figured out the principles they built the train on.

Doc couldn't have come up with it all on their own.

The components in the hoverboard could be refitted into a crude time machine

It's among their assets.

Jossed by the Telltale game, unless they bought a new pink Mattel hoverboard in the future for some reason.

Clara and Doc built a one-shot time machine and used it to go to the future first.

They were able to make only one trip, so they went to 2015 and could get all the parts they needed.

Doc Brown was named after himself.

The Doc's parents, a young couple new to America in the 1880s, changed their last name to Brown after meeting an inspirational and quirky blacksmith, and subsequently named their son Emmett after the blacksmith and encouraged him in scientific pursuits.

As stated in the movie, the Browns didn't come to Hill Valley until 1908, well after Marty and even Doc left the old west.

And according to the Telltale games, Doc's father was very much against young Emmett's interest in science and wanted him to go into law instead.

Doc and Marty leaving at the end of "OUTATIME" had a better explanation.

At the end of "OUTATIME", Doc and Marty see THREE Marties arriving from the future, ALL of them wanting their help. Such an event is just BEGGING to tear apart the time stream, according to Doc himself. So, what do they do? Leave the three behind as they go time traveling without them. An actual logical reason isn't given as to why they leave them, but if you think about it, a reason isn't needed.

For you see, just like the audience, THEY don't understand what the {bleep} is going on so they decide to leave as soon as possible. They WILL sort this out... only after they collect themselves to better understand the situtation. And hey, they still have a DeLorean time machine, so...

Conversely, because the first of the three Marties from the future let himself be seen by his younger self, it caused the parallel future timeline that the second Marty would come from, which then caused the parallel future timeline that the third Marty would come from. It could be seen from the fact that the second Future!Marty talks of the first Future!Marty as if his timeline's been erased, and the third Future!Marty is sick of the both of them. By ditching all three of them, the Doc and Marty of the Present hope to prevent the events that set the paradox in motion before a fourth Marty from a parallel future timeline shows up.

This is Fridge Brilliance. Future A!Marty comes back for whatever reason, creating a timeline in which 1986B!Marty apparently decides to eventually come back to that moment because things thereby eventually get screwed up (becoming Future B!Marty/"Evil Twin" Marty), which again screws things up for poor 1986C!Marty, who comes back from the future to settle things as Future C!Marty. Hopefully, 1986!Marty just decides at that point never to revisit that moment in time...

The timeline itself caused the DeLorean to malfunction in Part I, every time it did so, in order to prevent paradoxes.

The first time it malfunctions is shortly after traveling to 1955, when it breaks down in front of what would later become the Lyon Estates housing development, which conveniently has a large sign to block the easy view of the car from a road, and being in an undeveloped area is highly unlikely to be traversed until Marty and Doc can move the car (as it's a weekend, not even the construction or survey crews will be there). Having the starter malfunction prevents Marty from driving the vehicle into 1955 Hill Valley proper, which would garner attention of the wrong sort (which might in turn make it impossible, in some way, for Marty to have access to the vehicle on the night he absolutely needs access to the vehicle - remember, there is plutonium in it!).

The second time it malfunctions is just before the trip back to 1985. The timeline probably causes this because the timer is actually off slightly, and if Marty actually were able to start accelerating when the timer rang he would end up reaching the wire too early, which would cause innumerable problems.

The third time it malfunctions is just after Marty gets back to 1985. The timeline probably causes this to force Marty to go to the mall on foot, minimizing the chance that his earlier self could see him and potentially trigger a paradox. This also answers a Headscratcher question about why Marty only gives himself ten minutes of leeway: the timeline would ensure he couldn't interfere no matter how much time he gives himself. An hour of time, and the timeline might cause there to be a police patrol of the town square at 12:35 that morning. The property damage to the theater front, plus the fact that the DeLorean is not, strictly speaking, Marty's, would be enough for them to detain him at least until they can contact Doc and/or his parents, which would almost certainly be after the Libyan-shooting incident at 1:35. (It would probably take that long just for the paperwork, fingerprinting, etc., and that assumes Marty submits quietly which under the circumstances is not a guarantee.) He gives himself a day or more, and Doc informs him of the bulletproof vest and keeps him hidden until the event actually happens.

No, the timeline deliberately destroyed the DeLorean because otherwise the DeLorean would have been impounded by the police, because Marty has no way of getting it off the railroad tracks. All it takes is one cop to look inside it and realize it's a time machine, because the dash itself claims it traveled from a specific day in 1885! He'd either handing it over to the government or using it for whatever purpose he wanted. And a quick look in the history book will demonstrate that someone with the improbably name of 'Clint Eastwood' stole a train and drove it into a canyon at that exact day and time, and a time machine with a broken gasoline engine shows up from that day and time, so even the 88 mph requirement shouldn't be that hard to figure out. ('Why would they be pushing it down the track?' 'Maybe it has to be moving to work?')

And even without figuring out the time travel thing, it still has Mr. Fusion and a broken hover conversion, either of which could cause massive timeline changes. Basically, if the timestream doesn't destroy the De Lorean, there's going to be some major alterations to the timeline soon.

In at least one timeline, a daughter (or son) of Marty will marry a son (or daughter) of Doc.

This would explain the first Future!Marty using the expression "our great-great-grandkids" when talking to Doc. If one of Future!Marty's kids has kids with one of Doc's kids, their kids' kids (see what I did there? :-D ) will be both Marty's and Doc's great-great-grandkids.

In an eventual second season of the game, Marty and Doc will immediately return to 1931.

For two reasons. First, because it would be the cheapest possible cop-out, so it would be the most effective way to troll fans. Second, because Doc saying "The future can wait" means that they are going to the past again.

As a corollary, the whole incident with the three Future!Martys will never be mentioned again, for the same reason: to troll fans and make them rage.

And, of course, as previously established, Marty will never become any of those Marties because there's no way he'll become any of them at this point. Given enough time, they'll fade away, and Marty'll be fine with it because of Doc's 'you're the only real one, and the future is unwritten' philosophy.

Leather jacket future Marty is LP!Marty.

See the headscratchers page for the TP!/LP!marties confusion. LP!Marty will be the new Big Bad of season 2, trying to kill TP!Marty for stealing his place in life. Future Marty #2 is the Marty of the current alternate present as of episode 5.

The Telltale series will eventually end with Marty preventing Doc from inventing the flux capacitor.

The timeline will at some point become such a mess the only way to fix it is stop all of the time travelling from happening in the first place. If it's good enough for the card game...

This will culminate in Marty discovering that the Flux Capacitor was destined to be invented, and Doc invented it a bit later and went through a different time-machine-making process, culminating in a new first experiment not long after his return to the present. The player is given the option of sabotaging it, letting Marty's history repeat itself, or changing Doc's time travel experience for the better.

In the altered timeline that Marty creates through his trip to 1955, Biff has been castrated in the 30 years between then and the "good" future that the McFlys have

George McFly could have done this himself to get back at him for attempting to rape Lorraine, or this could have happened any way as a form of karmic justice. Some fans may say that this at least partially explain why Biff is somewhat less "manly" than in the original timeline. However, it definitely explains why Lorraine is (seemingly) okay with seeing her would-be rapist every day and with the fact that he also has keys to her house. She would (possibly) be cool with this because he is not only unable to even attempt this again, but he is also going to be reminded of this (and the fact that he works for his castrator if it was George who did it).

In the first film, Biff was planning on raping Marty.

"You caused three hundred bucks' damage to my car, and I'm gonna take it out of your ass," he says, before throwing Marty to his flunkies. He built up the necessary rage and lust beforehand, with the Ooh La La magazine and booze, while he was planning on attacking Marty at the dance, but Lorraine (who he'd been pursuing for weeks) presented herself as a more preferable target.

Not necessarily, it could be more in the sense of "I'm gonna whoop your ass", i.e. "beat you senseless", which is just as sensible. I think that's reading a little too much into that bit of dialogue, and probably is making too many assumptions about Biff's nature.

Never mind that his bad future self married three times to three women and there is no indication whatsoever of any other orientation. Even his 2015 self asks about "Marty Jnr's" grandmother.

Doc burned down his house for the insurance money

Look closely at the newspaper clippings at the start of the first film. We know that Doc is living in his garage and that the land was sold for a large sum of money. Doc claims to have spent the family fortune building the time machine. It's only reasonable to assume that he burned the house down and made an insurance claim. After that money ran out, then he sold the land to a property developer.

Makes a lot of sense when you realise just how slippery a character the Doc is. not only does he rip already stolen plutonium (which he has no legal right to keep hold of) but in the outtakes of the first film, 1955!Doc is seen bribing the police officer who asks him about the "permit" for his "weather experiment". Insurance fraud in the pursuit of his dream experiment is not exactly much different.

The reason why Doc is so cheerful despite everything

He has a goddamn time machine. His second order of business when Marty got back from 1955 was to retroactively cause all his enemies not to exist.

Doc is a fan of Carl Sagan because Carl succeeded where he had failed.

Carl Sagan's deservingness of his fame is something of a point of contention among the scientific community because of how little he has actually contributed to science. However, his immensive skill in getting people interested in science and in providing perspective and aiding in understanding is indisputable. Compare with Doc, whose only admirers were a teenage kid who broke into his garage and that kid's father, who only respected Doc because his son did.

This could potentially explain one of Doc's strangest choices...

Carl Sagan's Cosmos inspired Doc to choose a Delorean.

When the time came to put his flux capacitor into a vehicle, he realized that if anyone was ever going to take him seriously - something that had rarely happened for him - he'd have to capture their imaginations, just as Carl Sagan had with his TV series and its cool 'ship of the mind'. He waved off his own concerns about his integrity with what he believed also occurred to the people behind the show: you might as well do it with some style!

It's possible Jules and Verne were affected in some way by the constant time travel, and that frequent exposure to the time stream integrated new powers to the DNA of the Brown clan. As centuries passed, the descendents of Doc Brown made more time machines, eventually integrating space-faring capabilities into the machines. This new breed of humans decide to leave Earth at some point, and found their own, free and open society on a planet called Gallifrey. Down the line, a young man of a race known as Time Lords is visiting 20th century England and gets an idea for a ship design...

Marty's drag-racing crash in in the original timeline would've killed the father of Hitomi Shizuki when he was still a boy visiting Issei (first generation Japanese-American) relatives in Hill Valley. Hitomi of course becomes the Unwitting Instigator of Doom for Sayaka's (and the show's) Start of Darkness. But the Ripple Effect created when Marty avoided the crash caused the crash 26 years later that injured Sayaka's love interest's (also a budding musician) wrist, and eventually leads to her contract (and eventual Witchdom...which of course sets off a Domino Effect that destroys the world in one timeline). All their messing around with the space-time continuum had of course put considerable strain on it.

Of course in the previous version where Marty does crash, Marleen becomes a Magical Girl to help her struggling family and deeply depressed father...and eventually a Witch when she's arrested trying to bust out Marty Jr. in Timeline 1a and when Marty gets fired in Timeline 1b. One of the survivors of the crash (Hitomi's would've-been second cousin) became Marty's boss at his office job, initially forgiving and taking pity on him, but nursing a deep grudge that led to Marty's firing.

Before the time machine was invented, Marty was also rather unconfident (he didn't think anyone would like his audition tape), and wouldn't have gotten in that drag race in the first place. But as mentioned above, changing the past the first time around also made him rather more cocky and reckless.

I also wish Doc had never invented that infernal time machine...

As you might guess after watching this anime, an Incubator implanted the blueprints for the flux capacitor in Doc's head. He thought that with human nature being what he knows, humanity was simply unable to handle the responsibilities of time travel...hence it would prove a great way to harvest souls.

A man with the family name of Hill. They stopped calling it Hill's Valley after awhile out of laziness.

This is explicitly mentioned in Number Two, the first version of the script for the second movie. There's a scene in 2015 where Marty passes by a statue portraying "William Hill, founder of Hill Valley".

Doc is also responsible for creating his own family's original fortune.

Doc's family, the Von Brauns, moved to Hill Valley in 1908. Assuming that Doc Brown in 1955 was the same age as Christopher Lloyd at the time (47), then Doc was born that same year. At some point, Doc travelled to meet his parents in the past and inspired them to move to Hill Valley, giving them valuable information about possible business or investment opportunities, allowing them to make the money that he would later use to build the time machine.

Doc Brown is travelling through time in his train in order to keep paradoxes and deaths from occurring.

It's been covered many times before how the 1950s have tons of Martys, the 1985 that Marty ends up in at the end of Part I is completely different from the one familiar to Marty and therefore everyone there would be strangers to him, and all the weird things that happen that should change the timeline in numerous catastrophic ways.
However, there's one way around all the headscratchers and fridge horror: Doc Brown traveled to various points in time to nudge things in various directions so the timeline Marty ends up in at the end of Part III is nearly identical to the one he started out in at the beginning of Part I, with minor changes in parts of history Marty would know little to nothing about. As far as Marty knows, the two timelines are exactly identical. Thus, Marty faces no problems with his memories not matching up with others' memories, and the moral Doc utters that Marty's destiny is only what he makes of it still rings true, as the only changes Marty can observe are those which me makes without the use of time travel. As far as Marty can tell, it's all mundane normality, but he knows about the other timelines and thus knows more about the possible consequences of his actions, good and bad. He's free to forge his own future, but with more insight as to the impacts of his actions.

There is a God of Karma in the BttF Universe.

In the pre-movie version of the timeline, the Tannens have been giving Hill Valley a hard time (Mad-Dog the murderer, Biff the wanna-be rapist, to name two examples) for a hundred years or more. The GoK finally got fed up and used a pair of fairly decent chaps and their time machine to put the Tannen family through a Humiliation Conga, while rewarding Doc and Marty with better lives than those with which they started (Marty's family escaped loserdom, Doc got a family). Not Laser-Guided Karma, but definitely heat-seeking. Bonus sub-Guess:

"Red" Thomas was corrupt as Mayor.

He got on the GoK's bad side, too, which is why the Mayor in 1955 is a bum in 1985.

There will be another sequel.

With 2015 fast approaching and Michael J. Fox's return to acting, the timing's right...
It'll include such things as a Lampshade Hanging of "jigowatts" and how Part II saw 2015.

Biff didn't kill off Doc in 1985-B because he, to an extent, realised the Almanac's origin.

At first, all Biff knew about the almanac was that "some relative" knew a guy who could see into the future. With millions of dollars and the years passing, Biff eventually became more intelligent and started to realise how his Gray Sports Almanac could tell the future-then he met the wild-eyed professor Doc Emerett Brown. After interrogating him, Biff put two and two together and figured out that a time machine brought back the Gray Sports Almanac, and that Doc Brown will one day build it. Wanting Doc Brown to not be a threat yet needing his genius, he had Doc Brown committed and looked after in a makeshift duplicate of his lab. His cronies gave Doc the technology to design the Delorean, and had this timeline progressed Biff would've used it to go back and give himself the Gray Sports Almanac. Anything he's saying to Marty-A is partly him playing dumb

At the end of the first movie, the Doc of that timeline sacrifices the Marty of that timeline to avoid a time paradox.

Let's call the timeline at the beginning of movie 1985-A, and the Marty we follow throughout the movie Marty-A. Marty-A travels back to 1955-A, but when saves George from being hit by a car, the timeline changes into 1955-B. At the end of the movie Marty-A travels back to the the future of this timeline, i.e. 1985-B. He then sees the Marty who grew up in this timeline, i.e. Marty-B, being sent back to the past. Now, remember that Marty-B's past is the timeline where Marty-A appeared in 1955. If the events of 1985-B played out exactly as those of 1985-A, Marty-B travels back to the same 1955 where Marty-A was. So they'd both be in Hill Valley at the same time, and Marty-B would probably try to get back to the future the same way Marty-A did (by asking Doc Brown of 1955 to help). However, this would mean that Marty-B had a high chance of meeting Marty-A, and Marty-B might also change the past so that 1985-B never happens. To put it short, the chances of Marty-B either causing a paradox or messing up the timeline are pretty high. Even if Marty-B somehow managed to avoid changing the timeline and managed to get back to 1985-B, that would mean Marty-A and Marty-B both now exist in 1985-B, which would be a pretty awful situation. (Since George and Lorraine are technically Marty-B's parents, and Jennifer is his girlfriend, Marty-A would probably have to create a new identity and move out of Hill Valley.) Now, Doc-B realizes all this could happen, so he has to come up with a plan to avoid it. His only option is to set the timer of the DeLorean to some other year than 1955, to either send Marty so far back in the past that he can't change the lives of his ancestors, or so far in the future that his future version has already died. If he sends Marty-B to the future, he probably has to sabotage the DeLorean too, so that Marty can't get it to work again in order to travel back to 1985-B. Now, this a pretty awful thing for the Doc to do, since he's known Marty-B for much longer than Marty-A, but it's still better than the alternative. (All the Doc can hope for is that Marty-B get to live decent life in the time period he sends him to.) Since Marty-B isn't seen in 1955, nor does he come back to 1985-B, it means the Doc's plan worked.

Due to the delayed feedback effect in the movies and the butterfly effect from real life, Marty's actions in the first movie changed Jennifer's genetic makeup.

That's why she starts off as Claudia Wells in the first movie and has suddenly transformed to Elisabeth Shue by Part II. (Of course it doesn't explain the fact the same scene has played out twice in the subsequent movies with both actresses.)

Alternatively...

There is a missing movie between Parts I and II.

Originally, the second film was going to take Marty to the year 1967. Perhaps his meddling with events of that year causes Jennifer Parker to have the same father but a different mother. Marty goes back to 1985 after these events and the first scene of Part II happens a little later than it did at the end of Part I. Doc returns from the future after finding out that bad things still happen to Marty's kids, and the rest of the film takes place.

Her Majesty the Queen meets with an unfortunate car accident, not Princess Diana, in part II's 2015 timeline

After all, by 2015, Queen Elizabeth II would only be 89 by 2015, which given her mother's great age at her death, would mean she'd almost certainly be very much alive if she were eventually to die of natural causes. Only an accident would put Charles on the throne, and hence Diana as queen, so soon. (Of course how she survives her marriage to Charles is another matter- maybe he gives up on Camilla pretty quickly for the sake of fulfilling royal duty? Who knows...)

If Marty had disappeared, the timeline would eventually reset itself to the original anyway.

It's obvious that any changes made to the timeline will slowly begin to manifest themselves. Marty disappearing because he accidentally split up his parents represents an obvious change to the timeline- it's a reflection of the fact that he no longer exists. Since he can't then be around to split his parents up in the first place, this event will also eventualy be erased, and his parents meet up as normal.

The universe wouldn't be destroyed if Jennifer met herself.

It's just the Doc being paranoid, which has been seen to happen occasionally (like where he insists on not knowing anything about his own future, even when it will save his life, and later relenting. After all, this effect's possibility is only assumed because we might be inclined to take the Doc's word for it.

Or, he's simply referring to the disastrous effects on the timeline.

In the Biffhorrific timeline, the Internet as it is today does not exist.

Simply enough, most corporations that form the Internet are in California, which also turns out to be the state in which Biff Tannen and his heirs ravage. (This is implying that in the rest of BTTF 2, the Internet exists and is simply never seen, as it would require an entire scene.)

This would only apply to the future of the timeline- for the bit we see in BTTF 2, it's 1985, when most people hadn't heard of the internet in reality.

After Doc made his train time machine, he wrote the almanac.

He ensured that the race that Old Biff used to convince young Biff that it worked, but made sure the rest of it was completely wrong. Just in case, that way even if Biff got a hold of a time machine again, he would fail.

That wouldn't have helped much, as one doesn't need the whole almanac to make a killing; just the highly improbable bets. Old Biff could have set it up so he told Young Biff to mark anything that would yield more than a 100-1 win (e.g. Cubs winning the World Series 2015), and then given that list that he compiled to Young Biff, so he could bet and win.

Marty returning to Doc at the end of Bttf2 and the start of Bttf3 directly influenced his decision to put the ripped up letter of his death back together.

Throughout the majority of the first movie, Doc was adamant on not knowing what his future holds and rips up the letter explaining his death even as Marty pleads that his life depended on it.
However, fast forward to the start of the third movie and Doc has to once again help Marty out. During this brief time they have stumbled on his future self's grave, who had been killed in 1885 by Mad Dog Tannen. Marty now is adamant on saving Doc in 1885. My opinion is that 1955 Doc was touched by Marty's commitment on saving him. This, coupled with the fact that he now has knowledge that he will die at some point during this whole ordeal, which means that he knows too much about his future anyway, means that indeed regarding the letter Marty wrote, 'what the hell'.

Except he also did it in the timeline created at the end of BTTF 1, where Marty did not "yet" return to 1955 to stop old Biff, and consequently, Doc never interacted with Marty again until Marty grew up in his proper time.

Doc got the idea for the bulletproof vest from Marty.

He checked the historical records of the time where fut!Doc in the past should have died, and found out that a duel between Marty and Mad Dog Tannen instead occurred. The impressed locals likely recorded quite a few details, including the bulletproof vest.

Jossed by Bob Gale. During an interview about the game, he said that in the series, the effects of a time jump are never shown before showing the time jump itself. Meaning that LP!Doc used a bulletproof vest despite living in a timeline where the events with Marty and Doc in 1885 never happened.

While he could have avoided being shot entirely once he read Marty's note (by sabotaging the Libyans somehow, for instance, or finding another source of plutonium), it would have created a paradox - if Marty didn't see him get shot, he'd have no reason to write the note (or accidentally travel to 1955, for that matter) in the first place. Doc is too concerned about damaging the fabric of space-time to ignore a paradox of that magnitude - the only way he could survive without risking tearing the universe inside out would be by letting Marty believe the Libyans killed him long enough for Marty to travel back in time. If Marty's note mentioned that he'd been shot in the chest, he knew a bulletproof vest that could handle their ordnance would do it. He may have also managed to contrive a method of swapping their ammunition with blanks (to minimize the risk of bullet fragments from hitting something exposed or some minor change making the Libyans pull off a head shot this time around), in which case the vest was a backup in case they noticed or used different weapons than he expected.

Some time after Btt F 1, Doc obtains the device which sends people to sleep and causes short term memory loss, with those it's used on often attributing memories to dreams. He also damages the DeLorean, the flux capacitor needing repair. As Doc doesn't trust himself to tamper with such a volatile component by himself, and knowing that no one else on the planet knows how it works, he travels back to a past version of himself. To prevent the timeline being disrupted, he wipes their memory afterwards, but they retain some of the memories... Leading to the idea for the Flux Capacitor and how it works coming to Doc Brown in a dream.

The Marty and Doc of most of BTTF Pt 2 are insane. Their delusions just happen to be right.

Given: Had Marty failed to make his parents fall in love, he would have endangered all existence by creating a paradoxical world where he was not born and could not have interfered with his parents falling in love. Given: It is a remarkable coincidence that George and Lorraine had the same three kids with the same three names and substantial, but ultimately inconsequential, differences in their lives (i.e. Dave has a better job). Given: We must eliminate the fact that Marty and Jennifer simply grew from age 17 to 47 and had two kids between 1985 and 2015 in the timeline in which Marty Sr poses as Marty Jr, because it is impossible, therefore another explanation—however improbable—made it possible for it to appear that they did.

When Marty and Doc travel back in time to 1985, they find themselves in an alternate reality where Hill Valley is a miserable Hell Hole. Okay, but how on Earth did Marty & Doc get ahold of a flying car time machine in the first place? How could they remember a past that Biff had already erased? Why were they in 2015 to begin with?

Remember that the "alternate" 1985 was the product of an alternate 1955 created by Biff. An alternate 1955 by which Doc Brown had still conceived of the Flux Capacitor, and in which George and Lorraine had still been fixed up by "Calvin Klein," followed by an alternate 1968 in which Marty and Jennifer were still born and an alternate 1972 in which George was murdered and Doc was committed. It just, for some reason, involved traveling to 2015 where Marty & Doc were dragging Jennifer into the time machine he piloted.

In this history, suppose Doc was released from the mental hospital at some point prior to 1985 and that Marty's hatred of his stepfather (perhaps even his suspicion that he'd killed his real father) had driven him into a mental state that was fragile, but that Biff—being a jerkass—simply would have just seen as lazy and stupid. It's consistent with Marty sending Biff to Switzerland. A neutral country where people have bank-accounts to avoid taxes or however it works. Maybe Doc would flee there to avoid a stigma he might have in the U.S. but not there. Perhaps his brilliance would permit him to work in a fancy private school and Marty is his student.

That may sound farfetched, but the films aren't exactly clear on the circumstances in which Marty & Doc met in the first place anyway.

Okay, so Doc builds a version of the time machine because he has this strange delusion that Biff somehow got his paws on an almanac from the future that helps him win bets. After-all, if you look closely, there's a picture of him where he's got an almanac from the future tucked away in his pants. Doc learns of Marty's connection to Biff and influences him to buy into his "crazy" theory.

This involves building a time-machine identical to the one we all know and love, complete with the flying. Okay, but how? I dunno, they somehow manage to get aboard a plane with falsified documents. Remember, this is taking place over a period of time prior to October 21, 1985. They could have met as early as 1982 if Marty started the private school at age 14. Anyway, they arrive at Doc's dilapidated mansion, buy a DeLorean and build the thing using his old designs for the FC. The important thing is that the have it completed by October 21, 1985 and take their journey on that day (otherwise, their decision to return on that day becomes a little arbitrary and Biff doesn't end up traveling back in time on that date anyway). Oh, and they've somehow convinced (or forced) Jennifer along. Why? Part of Doc's delusion. How? I don't know. She could also be a troubled youth. Now, at this point, the story of Marty trying to save Marty Jr from joining Griff's gang doesn't matter. ALL that matters is that Griff ends up with the almanac on that day, and decides to go back in time on that day to that very day of November 5, 1955 (a day during which, Marty and Doc's delusions lead them to believe that Marty is supposed to take Lorraine to the dance, etc) and Marty must blame himself for having the idea to make money off of the almanac. In fact, driven crazy by all the crazy stuff going on, maybe Doc's managed to convince Marty that George is still alive. Almost forgot: it's also important that Biff lives until 2015. So when he leaves the DeLorean in pain, and he's fading away? Um... yeah, aliens got him.

So anyway, on October 21, 2015, they find that Biff is frequenting the Café '80s (or whatever it might be called) and he overhears them talking about the time machine. They're talking blatantly so that he can hear them. By this point, Marty had bought the almanac. Here's the disturbing part: they've tied Jennifer up in such a way that it'll be easy for her to escape once they get to the Lyon Estate. They leave the DeLorean open for Biff to steal after she's escaped and once she escapes to a nearby house, they flog her and bring her back. Why? I don't know, but there's Unfortunate Implications. Remember, though, it doesn't even have to be the McFly house.

So Biff steals the car and gives it to himself, leaving the time loop mostly the same. The emotions he's feeling might be different, but his actions while he's there are almost identical. The timeline up to Oct 21 is virtually identical to what I described. Marty & Doc's delusions are the same. They head back and Marty is genuinely surprised by the world around him, not because he remembers it first hand, but because Doc had been working him. Making him think he remembered it. Not through some gizmo that changes peoples' minds, but because he's just that manipulative.

Marty and Doc go through everything we see in the movie with Marty's delusions and Doc's influence on him. Everything we see in the film happens, which means that once they end up in 1955, they create—yes—a new timeline in which the stage was set for the history established by the end of the first film. Their delusions become true. Marty really was raised by George from 1968 to 1985. He really did have a girlfriend named Jennifer. What he thought he knew, he really did know and so the film was compiled from three different timelines.

In the Back to the Future universe, or at least the 2015 timeline shown in the second film, Laserdiscs achieved mainstream popularity in America.

Contrary to another WMG above, the discs shown trash-compacted in the back alley definitely include Laserdiscs. In Real Life they were very much a niche market product in the West, but for them to be thrown away in such significant quantities would imply they would have to have a popularity at least akin to VHS (notoriously difficult to get rid of in Real Life) if not greater. So, either they were popular to begin with (we just never see the fact on-screen) or the experienced a sudden jump in popularity in the 1990s.

In 2015, Jennifer is a shoplifter.

When she returns home, she looks around as if to make sure nobody is looking as she carries shopping bags.

Or, she's a compulsive shopper.

Which would produce a similar reaction- she's hiding her addiction from her family.

Marty and Jennifer's kids are clones.

Jennifer was unable to have kids, so they used future technology to clone Marty. Technology was not advanced enough to combine genes of two people, so the daughter was a Marty clone with its gender changed. Jennifer did not want a clone because she believed that she would faint if she ever saw someone who looked exactly like her.

The Michael J. Fox Show is Marty's new future.

In a new timeline, Marty's music career did not take off and Jennifer left him. He changed his name to Mike Henry and moved to New York, where he had a new wife and kids who do not look exactly like him. There will be an episode that takes place October 21, 2015.

When Ito T. Fujitsu tells Marty, "You are Terminated!" he really means that a Terminator is on its way to kill Marty. In the timeline of Terminator Salvation, there are T-600s by 2016, so maybe that is what would have been sent.

Everything before Marty wakes up at the end of Back to the Future is a dream.

Marty was merely surprised about how different his family and Biff were because his dream of going back to 1955 was so convincing. In fact, it was so convincing that he imagined what might have happened afterward.

Everything after Marty goes to bed at the end of Back to the Future is a dream.

He did go back in time to 1955, but his family life was not drastically different from the original timeline. He also dreamed of the sequels, in which Jennifer's physical appearance is inconsistent.

Marty imagined Doc.

Neither Marty's parents nor his siblings acknowledge Doc Brown. He imagined him because he was so bored with his life.

Except that Strickland acknowledges Doc talks about him like he's a real person.

Doc Brown is Professor Plum.

In 1955, after the events of the Clue movie, Professor Plum got a new identity and chose a last name that also referred to a color. He even made up an entire family history for himself.

Or Doc Brown is his real name.

George McFly created Star Trek and Star Wars.

What if Marty McFlywas careful about making sure that he does not mention things from the future to his father? There is no concrete evidence to suggest that Star Trek and Star Wars even existed in the original timeline. After Marty scared George into getting together with Lorraine, George decided to pursue a career in science fiction. At first, he tried to publish A Match Made in Space with mentions of "Darth Vader" and "the planet Vulcan." However, publishers were not interested right away, which is why it was not published until 1985, 30 years after Marty gave him the idea. He decided to shelve the book and pitch his science fiction ideas for television. As it turned out, some of the stories that George had written in high school that he did not want Marty to read were the basis for Star Trek. He pitched the idea for the TV series and it became a hit. Since it seemed that his book would never be published, he went ahead and named a planet "Vulcan" and included the hand gesture that would be used by Vulcans. When Star Trek went off the air, he turned toward a career in film. As an alternate universe George Lucas, he wrote various drafts of the script for Star Wars and named a character "Darth Vader." After finishing the original trilogy, George once again showed publishers A Match Made in Space. Since his name was more well known by that time, they agreed to publish it. Since he had already referenced Vulcans and Darth Vader in his previous works, he had to change the names to make it clear that this was a separate story. The book went on to spawn a series of its own.

Needles had called Marty a chicken all of his life.

Marty's need to disprove claims that he is a chicken is a result of a Noodle Incident. Or should I say Needles Incident?

Alternatively...

Marty was first called "chicken" in the second timeline.

After changing history in the first film, Marty ended up in a timeline in which he obtained memories of being called chicken all of his life, something that had not happened in the original timeline. Perhaps the now brave George McFly ended up being dickish enough to call Marty a chicken whenever he was afraid to do something in the second timeline.

It's not so much that his memories or personality rippled, it's that deep down Marty was always a self assured jerk to the point of arrogance but he grew up afraid to take a chance. After time traveling, not only did he now feel like a bad ass, seeing his new future where he grows up wealthy and happy flips a psychological switch in him, bringing out that aspect of his personality.

Doc did awaken the dead with that blast.

The sound of the blast itself was sent into the future where it awoke The Walking Dead, thus changing the 21st century.

Marty's new personality in the altered timeline was responsible for his kids.

In alternate 1985 Marty is the son of rich, successful, cool parents. This causes Marty himself to become stuck up and spoiled, which is why he now can't stand being called chicken. Being a spoiled kid he expects life to cater to him and hand him all his shit on a silver platter. Then he gets in the car crash and breaks his hand and grows up to become a shlub. Now bitter and resentful he does what a lot of bitter and resentful parents do, he berates and belittles his kids. This causes his son to grow up to become a wimp he is bullied by Griff into committing a crime, Marty Jr. is thinking about doing it mainly to prove his dad wrong.

(This applies for time travel in general) People born BEFORE a temporal incursion DO notice the changes in the timeline.

So for example everyone born before 1985 would notice the changes occur around them. However no 'sane' person would understand what just happened. This leads to many neurosis, and mental illness'. Your grandpa doesn't have alzheimers, it's that originally things were different and he remembers that original timeline. Conspiracy theorists begin to crop up because they noticed things changed around them and can't explain it. Paranoids are remembering old enmities and conflicts that no longer exist in the changed timeline. Also, humans would have perfect memory and recall EXCEPT the temporal incursions keep changing things so memory seems inaccurate, you look at a picture and notice you're wearing a blue dress in it when you remembered it being an orange dress...because IT WAS, up until Doc and Marty, or the Doctor, or the crew of the Enterprise or the Time Traveler's Wife's husband went back in time and caused a temporal incursion. History books aren't innacurate, history has changed since they were written. There is no ripple effect on memory, we all notice the changes and without time travel humans would be more mentally stable, have perfect memory recall and all history books would perfectly accurate.

Based on this and the fact Marty stayed in 1955 for a whole week before returning to the very same day he left, it took exactly one week after Marty's return before George, Lorraine and Biff to remember how their lives used to be before Marty messed with their past. Remembering a former life as a white-collar worker who made a living by taking credit for George's work must have compounded 2015!Biff's bitterness. He probably also figured out Doc's Time Machine is the reason his life changed and decided his own attempt to change his past would be a case of "two wrongs make a right", or "left" if nobody corrected him on that specific saying. Upon checking records of his life prior to 1985, Biff figured out when his life became different from what he remembers and it was no mere coincidence that his 2015 self went to the day of the dance that made George and Lorraine a couple.

Um Doc worked with terrorists to steal nuclear material...and we the audience just gloss over the implications of that.

Did any people get killed to get the plutonium? Did he have to work his way up the terrorist underground by helping them with other, successful, acts to gain their trust and support? The implications of this can be all over the place and paint a dark, dark picture of 'at what cost' the time machine. HOWEVER in Doc's mind I'm sure it was all morally justified because, TIME MACHINE! No matter what he did, no matter how much was stolen, no matter how many people died, he just kept telling himself, 'once my time machine is made I'll just go back and fix it'. Doc Brown may have been actually crazy, driven slightly mad by the guilt and anxiety of what he had done, betting it all on faith that his invention would work. Heavy.

Part of his decision to destroy that 'infernal machine' is not only because of the damage it can cause to the space/time continuum but because of the death and theft it has already sown. In the end part of what drives him to love Clara and raise kids is that in the face of all the misery his machine has caused he wants to bring new life and happiness into the world. In the end he decides to rebuild the time machine because he realizes if he doesn't use it for good then all those lives and all that misery was for nothing, so the his ultimate redemption is to fly around in time with his loving family and right that which once went wrong to make up for his mistakes...but without disrupting the time/space continuum in doing so.

What happened to those Indians?!

Marty travels back to 1885 and smack into a small army of Indians on the war path, who just run past him. Um, that's a big matzo ball just hanging out there. I mean they straight up just saw him driving around, one of them even shot the car with an arrow, and then, from their perspective, he just disappeared. The cavalry did run past him to but they didn't really see anything.

Doc Brown is a relative of Peri Brown from Doctor Who.

Emmett Brown is Peri Brown's great-uncle. Peri met The Doctor in 1984. Sometime during her travels, she returned and told Doc about her adventures through time and space. This inspired Doc to get back to making a time machine, which he did in 1985.

Clara was a Time Traveler even before Part III, or at least had contact to some

Claras reaction to Doc Browns claim, that he had build a Time machine and travelled with these from the future to her "now" (the year 1885) is like someone who was culturally exposed to popular science Fiction about Time Machines (e.g. she hears the Term, knows immediatly what it means, and think it is something from science fiction). There is just one Problem with that: the Term "Time Machine" was introduced und popularised by H.G. Wells novel "The Time Machine", published in 1895, ten years after the supposed Time Period Clara is from. Even H.G. Wells short story "The Chronic Argonauts" (acording to Wikipedia " the first well-developed use of a machine constructed to travel through time (a "time machine") in science fiction") wasn't published until 1888, three years after the 1885 setting. There is simply no way, that somebody from the year 1885 would know exactly what the Term "Time Machine" means, and treat it like some Science-Fiction stuff, since the Term wasn't introduced for several more years. That left just three possibilitys: 1) Clara is a Time Traveller from sometime beyoined 1895, 2) Clara already had contact to Time-Travel-Science-Fiction via real Time Travelers, 3) (possibly) due to further meddeling with the Time Line, Time Travel-Fiction within the Back-to-the future-Universe exists at least a few years before it does in ours.

While it's not likely (given that it had only been a couple days since she got to town), it's possible that she - unknowingly - had just come into contact with an artifact of time travel. It wouldn't be out of character for Doc to have a copy of The Time Machine in the DeLorean, perhaps with the intention of eventually going to some point shortly after 1895 to get it signed. He could have loaned it to her without thinking about the possible ramifications of it being seen a decade early. Even if she hadn't started reading it, that would be enough for her to recognize the term.

You can never 'fix' a timeline and there are no parallel ones either

BTF Rodenberrian physics shows that there are no parallel time lines, or else there would be no fading picture. Each time you travel back in time it overwrites the future from that point. However despite what they think they did, you cannot restore a timeline. You can only overwrite an overwritten timeline with one that resembles your original timeline close enough.

The 2015 Jennifer was cheating on Marty.

In that future where Marty became a bitter shell of the man she loved (not to mention the shitty wedding and the way he treats their children) has lead Jennifer to look for love in other places. It would certainly explain why Marty would have a hard time keeping track of her, as well as his sarcastic comment of how they were like a couple of teenagers. Jennifer's guilt of the affair has lead her to being a tranq.

To add insult to injury, she could be cheating on Marty by having an affair with Needles.

Marty is the reason that "heavy" became slang for something serious.

It's noted with a similar meaning on sites about slang in the 60s. In the original timeline it may have started in the '80s, but Marty introduced it early - it just took a little time for it to become common slang outside of Hill Valley.

Long after forming a band together, Billy Gibbons, Dusty Hill, and Frank Beard were startled to learn they had distant relatives in frontier times who not only were all musicians, but also played together. They came into the possession of sheet music for an original composition written by their ancestors, and after learning to play it themselves, they turned it into their song "Double Back". Alternately, ZZ Top were also time travelers - they went back to the old west hoping the music scene there would give them some inspiration for new songs: They ended up traveling with musicians of the time and wrote what became "Double Back" there.

How the flux capacitor works...

It temporariliy stores a large amount of electrical energy as a conventional capacitor does, then discharges it as gravitational energy, possibly somehow generating exotic matter. Basically creating a wormhole big enough and lasting long enough to transport a Delorean-sized object travelling at 88mph through time.

88mph is significant.

Following on from the previous WMG, it's not random but is the speed at which the Delorean must travel to get through the wormhole generated by the time circuits before it naturally collapses. Doc Brown calculated it as the necessary speed based on the length of the car and the projected time the wormhole would stay open.

Doc already had the bulletproof vest in the original timeline.

He might be crazy but he's not stupid. At least not to the point he'd think the terrorists wouldn't seek retaliation. Marty simply didn't have a chance to see it for himself before escaping to 1955. Since the new timeline's Doc doesn't remember this, he's not sure if Marty's warning was needed or not.

Marty would become a famous rock star in the original timeline.

One of his bandmates or his girlfriend would send a demo tape behind his back or he'd be told of how a similar fear of rejection was what made a loser out of his Dad. Also, Needles wouldn't have dared a carless person to that race so Marty wouldn't have suffered the accident that ruined his career in the future shown in the second movie.

That timeline's Biff is established to be a drunk driver in 1985. Had his past not been changed, he'd have died in a car crash he caused between 1985 and 2015.

Marty's memory is immune to Ripple Effect even when the effect is caused by changes he's not involved with.

Doc states that people who are outside their time when history is changed don't have their memories altered to fit the new reality. When Marty returns from his first travel to 1955, he returns to the same day he left despite having spent one week in 1955. That means he's one week behind his own time and thus his memory won't be altered by the consequences of time travels done without him.

Marty and/or Doc had something to do with Lady Diana's infidelity being exposed

After the second movie, they did some time travel that somehow caused her to be exposed. If not for that, Prince Charles wouldn't have divorced her and she wouldn't have died from a car crash.

Several fans will be watching the second movie on October 21, 2015

That's the day Marty and Doc went forward to. Fans everywhere want to compare the writers' predictions to what really happens. Most of them want to see if, contrary to their expectations, Queen Elizabeth II will be around.

Charles is dead in the 2015 from the second movie

Some fans ask why "Queen Diana" would go to Washington without her husband. It turns out he died at some point of history between becoming King Charles III or King George VII and 2015. He must have become King otherwise his Princess consort would never become Queen consort.

Changes to the timeline only ripple forwards

I may be overthinking things here, but it is in my nature.

This might seem like an obvious statement, because changes in the past should only progress forward linearly, but it has implications for time travelers. Essentially, changes to the timeline do not affect time travelers further back in the past. Objects (such as newspapers, matchbooks or photograps) and people from the future will change as history is altered but (as is seen in the movie) the changes only occur after interference in the past.

First, consider the implications of the 1985A of Part 2. With the Doc of that timeline institutionalized, the Marty of the timeline (supposedly in Switzerland) is unlikely to have taken accidental trip back to 1955 (and he would certainly have no flyer soliciting donations to save a clock tower that no longer exists). Nonetheless, when Marty and Doc go back to 1955, the Part 1 Marty is still there and going through the same events as in the first movie. This might seem like a paradox, but it makes perfect sense if changes to the timeline only go forward: Biff did not change history until November 12, so Marty's arrival on November 5 and all of the events that followed remain part of the past. This also means that, if asked, that Marty would always report that his father is a wimp and that Biff trashed the car; the change to his parents' histories did not change until after his arrival, so he would always remember his original history.

Note that the original Marty's continued existence after Biff's book delivery can be attributed to a Delayed Ripple Effect.

Based upon this hypothesis, Biff could have retroactively prevented Marty's first trip through time if he had given himself the book some time before November 5, 1955. Doing so would have allowed the timeline changes that his actions created to reach November 5, thus erasing Marty's trip from history altogether. Since he chose November 12, though, the changes that he made could not ripple "back" to November 5, preserving Marty's presence in that past.

This also explains why Doc in 1885 does not know of his impending murder by Buford Tannen despite his younger self learning of the event in 1955. When he was accidentally sent to the past, his younger self knew nothing of those events. If changes to the timeline only move forward, the Doc of 1885 would only know of his history as it was before he was sent back in time; he would not be aware of any changes that were made after he left 1955. Possibly, Doc's memories were adjusted once he traveled to some point after 1955.

I admit that this is not a perfect explanation, as it does raise some questions.

That theory being true proves Doc right when he told Marty that going back to 2015 to prevent Old Biff from stealing the Almanac and the Time Machine wouldn't undo the harm he caused by doing so.

One question: If asked before his time travel adventures, the Marty of the post-BTTF 1 1985 would probably report that his parents are successful and that Biff runs an auto detailing company; what would happen, then, if a time traveler stowed away in the DeLorean on the night of Marty's first trip through time and then, once in 1955, asked Marty about his parents? Based upon my above hypothesis that the Marty in 1955 is always the same, this would create complications. Still, an argument could be made that stowing away in the DeLorean itself changes history as of 06:00 on November 5, 1955 and thus it could update the Marty of that time. On the other hand, it could create a Time Crash.

"Clint Eastwood" was still regarded as the coward of history.

Let's see: he has never fired a single shot to Buford Tannen (or to anybody besides those dummies), avoided the shooting with him for as long as possible and even though the outcome appeared to be a win (Buford was K.O.'d and sent to jail), "Clint" still proceeded to go down a cliff (hence "Eastwood Ravine"). Meanwhile, Buford's life couldn't change that drastically, as Biff, his great-grandson, still likes the Old West in the modified 1985 (he compliments Marty's outfit).

The only advantage the realClint Eastwood would have while setting up his career is that cowards tend to be forgotten in history, and no one would have compared him to a figure that only appeared for a week in 1885 in a little-known town, and even if the link was discovered, the real Clint could have dismissed it as the two "not being related".

Doc's 1955 self was surprised at seeing his name at a tombstone from 1885 and he knew the buried Emmett Brown couldn't be just an ancestor who had the same given name as him because his family used to known as Van Braun before World War I. Having never traveled in time by then, Doc's 1955 self would remember no timeline other then the one where Buford shoots his future self in 1885 and it not affecting his family supports the theory about Clint Eastwood.

Buford killing Doc was Fate's Xanatos Gambit to minimize the damages caused by Doc while stranded in the past.

Fate doesn't like it when people from the future are stuck in the past and Doc had already damaged history by saving Clara's life. Fate realized that either Marty would find out and get back in time to rescue Doc or Doc's death wouldn't be prevented. Either way, Doc would be unable to cause more damages to history.

Look at it from their perspective. "Calvin" spent the entire time trying to set them up, he freaked out every single time Lorraine tried to flirt with him, the entire kissing scene ended up being viewed as familial rather than romantic, and he even remarked in the car about not being sure he could go through with the expected behavior in that situation. While the audience knows Marty wants to ensure his future existence and is creeped out by the idea of hitting on his mother, they don't know that. Chances are that, when they look back, Lorraine and George might assume that the reason why "Calvin" behaved like that was due to him not being interested in girls. They might even think that he was staying with Doc for a while because his parents kicked him out when they figured it out or something.

Marty being called chicken

comes from the general habit of Tannens to taunt their opponents into attacking them, as evident in all three films. While in the original timeline no McFly ever stood up to a Tannen and therefore the insult was unknown to the McFlys. However, once George started to take a stance against Biff, the latter took to goading him into further fights. The new, self-conscious George would not have it, therefore would beat Biff up each time (did you really believe Biff gave up after one lucky punch?) and then raise his son with the same Berserk Button ("Don't let them call you chicken, son.")

Marty caused Doc to fall while hanging his clock

In the diner in 1955, Marty slips into a phone booth and is relieved to see Doc's name in the phone booth. "Good, you're alive." He dials the number...

Meanwhile, Emmett Brown is perched on his toilet, hanging a clock. The porcelain is slightly wet. Suddenly the phone rings, startling Doc and causing him to slip. He conks his head and is knocked unconscious.

Meanwhile, at the diner, a frustrated Marty can't get anyone to answer and hangs up the phone.

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